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Influence of dislocations in the GaN layer on the electrical properties of an AlGaN/GaN heterostructure 下载免费PDF全文
This paper reports on a comparative study of the spatial distributions of the electrical,optical,and structural properties in an AlGaN/GaN heterostructure.Edge dislocation density in the GaN template layer is shown to decrease in the regions of the wafer where the heterostructure sheet resistance increases and the GaN photoluminescence bandedge energy peak shifts to a high wavelength.This phenomenon is found to be attributed to the local compressive strain surrounding edge dislocation,which will generate a local piezoelectric polarization field in the GaN layer in the opposite direction to the piezoelectric polarization field in the AlGaN layer and thus help to increase the two-dimensional electron gas concentration. 相似文献
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利用方势阱模型对InxGa1-xN/GaN MQWs结构的光特性进行了量子力学定性理论分析.并在MO源流量恒定条件下,在570℃~640℃范围内进行了不同生长温度的多量子阱制备实验,对InxGa1-xN制备过程中的In组份掺入效率的温度依赖关系进行研究.通过对制备样品的PL谱测量分析,得到了587℃~600℃的In组份最佳掺入温度区间. 相似文献
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This paper reports that (Ga, Mn)N is prepared using implantation of 3at.% Mn Ions into undoped GaN. Structural characterization of the crystals was performed using x-ray diffraetion(XRD). Detailed XRD measurements have revealed the characteristic of Mn-ion implanted GaN with a small contribution of other compounds. With Raman spectroscopy measurements, the spectra corresponding to the intrinsic GaN layers demonstrate three Raman active excitations at 747, 733 and 566 cm-1 identified as EI(LO), A1 (LO) and E~, respectively. The Mn-doped GaN layers exhibit additional excitations at 182, 288, 650 725, 363, 506cm^-1 and the vicinity of E~ mode. The modes observed at 182, 288, 650 725em 1 are assigned to macroscopic disorder or vacancy-related defects caused by Mn-ion implantation. Other new phonon modes are assigned to Mnx-Ny, Gax-Mny modes and the local vibrational mode of Mn atoms in the (Ga, Mn)N, which are in fair agreement with the standard theoretical results. 相似文献
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This paper reports that the Raman spectra have been recorded on the metal-organic chemical vapour deposition epitaxially grown GaN before and after the Mn ions implanted. Several Raman defect modes have emerged from the implanted samples. The structures around 182 cm-1 modes are attributed to the disorder-activated Raman scattering, whereas the 361 cm-1 and 660 cm-1 peaks are assigned to nitrogen vacancy-related defect scattering. One additional peak at 280 cm-1 is attributed to the vibrational mode of gallium vacancy-related defects and/or to disorder activated Raman scattering. A Raman-scattering study of lattice recovery is also presented by rapid thermal annealing at different temperatures between 700°C and 1050°C on Mn implanted GaN epilayers. The behaviour of peak-shape change and full width at half maximum (FWHM) of the A1(LO) (733 cm-1) and E2H (566 cm-1) Raman modes are explained on the basis of implantation-induced lattice damage in GaN epilayers. 相似文献
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采用密度泛函理论体系下的广义梯度近似GGA+U平面波超软赝势方法,在构建了纤锌矿结构的InN超胞及三种不同有序占位Mn~(2+),Mn~(3+)价态分别掺杂InN超胞模型,并进行几何优化的基础上,计算了掺杂前后体系的电子结构、能量以及光学性质.计算结果表明:Mn掺杂后体系总能量和形成能降低,稳定性增加,并在费米能级附近引入自旋极化杂质带,体系具有明显的自旋极化现象.掺杂不同价态的Mn元素对体系电子结构和磁学性质产生了不同的影响.电子结构和磁性分析表明掺杂体系的磁性来源于p-d交换机制和双交换机制的共同作用,Mn~(3+)价态掺杂有利于掺杂体系的居里温度达到室温以上.与未掺杂InN相比,不同价态Mn元素掺杂后体系的静态介电函数显著增大,掺杂体系介电函数虚部和吸收光谱在低能区域出现了较强的新峰,分析认为这些新峰主要来自与费米能级附近自旋极化杂质带相关的跃迁. 相似文献
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Degraded model of radiation-induced acceptor defects for GaN-based high electron mobility transistors (HEMTs) 下载免费PDF全文
Using depletion approximation theory and introducing acceptor defects which can characterize radiation induced deep-level defects in AlGaN/GaN heterostructures,we set up a radiation damage model of AlGaN/GaN high electron mobility transistor(HEMT) to separately simulate the effects of several main radiation damage mechanisms and the complete radiation damage effect simultaneously considering the degradation in mobility.Our calculated results,consistent with the experimental results,indicate that thin AlGaN barrier layer,high Al content and high doping concentration are favourable for restraining the shifts of threshold voltage in the AlGaN/GaN HEMT;when the acceptor concentration induced is less than 1014cm-3,the shifts in threshold voltage are not obvious;only when the acceptor concentration induced is higher than 1016 cm-3,will the shifts of threshold voltage remarkably increase;the increase of threshold voltage,resulting from radiation induced acceptor,mainly contributes to the degradation in drain saturation current of the current-voltage(I-V) characteristic,but has no effect on the transconductance in the saturation area. 相似文献